Dental caries is a disease in which minerals of the tooth are dissolved by surrounding bacterial plaques. A caries
process present for some time may result in a caries lesion. However, if it is detected early enough, the dentist and
dental professionals can implement measures to reverse and control caries. Several optical, nonionized methods have
been investigated and used to detect dental caries in early stages. However, there is not a method that can singly detect
the caries process with both high sensitivity and high specificity. In this paper, we present a multimodal imaging
system that combines visible reflectance, fluorescence, and Optical Coherence Tomography (OCT) imaging. This
imaging system is designed to obtain one or more two-dimensional images of the tooth (reflectance and fluorescence
images) and a three-dimensional OCT image providing depth and size information of the caries. The combination of
two- and three-dimensional images of the tooth has the potential for highly sensitive and specific detection of dental
caries.

Detailed morphological and cellular information relating to the human tooth have traditionally been obtained through
histological studies that required decalcification, staining, and fixation. With the recent invention of multiphoton
microscopy, it has become possible to acquire high resolution images without histological procedures. Using an epiilluminated
multiphoton microscope, we obtained two-photon excited autofluorescence and second harmonic generation
(SHG) images of ex vivo human tooth. By combining these two imaging modalities we obtained submicron resolution
images of the enamel, dentin, and the periodontal ligaments. The enamel emits endogenous two-photon
autofluorescence. The structure of the dentin is visible from both the autofluorescence and second harmonic generation
signals. The periodontal ligament composed mostly of collagen can be visualized by SHG imaging. We also
constructed three dimensional images of the enamel, dentin, and periodontal ligament. The effectiveness of using
multiphoton and second harmonic generation microscopy to obtain structural information of teeth suggest its potential
use in dental diagnostics.

Failure of endodontic treatment is commonly due to Enterococcal infection. In this study influence of chemical
treatments of type-I collagen membrane by chemical agents commonly used in endodontic treatment on Enterococcus
faecalis cell adherence was evaluated. In order to determine the change in number of adhering bacteria after chemical
treatment, confocal laser scanning microscopy was used. For this, overnight culture of E faecalis in All Culture broth
was applied to chemically treated type-I collagen membrane. It was found that Ca(OH)2 treated groups had statistically
significant (p value=0.05) increase in population of bacteria adherence. The change in adhesion force between bacteria
and collagen was determined by using optical tweezers (1064 nm). For this experiment, Type-I collagen membrane was
soaked for 5 mins in a media that contained 50% all culture media and 50% saturated Ca(OH)2 . The membrane was
spread on the coverslip, on which diluted bacterial suspension was added. The force of laser tweezers on the bacteria was
estimated at different trap power levels using viscous drag method and trapping stiffness was calculated using
Equipartition theorem method. Presence of Ca(OH)2 was found to increase the cell-substrate adherence force from
0.38pN to >2.1pN. Together, these experiments show that it was highly probable that the increase in adherence to
collagen was due to a stronger adhesion in the presence of Ca (OH)2.

We have been developing a unique optical frequency domain reflectometry (OFDR)-OCT based on Mach-Zehnder interferometer using a discretly swept superstructure-grating distributed Bragg- reflector (SSG-DBR) lasers developed for telecommunication field. Our previous measurements at C-band wavelength (1529 to 1568 nm) revealed good quality of data. In this work, we extend measurements with a L-band (1560 to 1600 nm) SSG-DBR source at faster scanning speed of 0.5 &mgr;s/step compared with former 10 &mgr;s/step. In spite of the faster scanning, we can observe better quality of OCT images of hard and soft dental tissues in-vitro and in-vivo measurements.

In this work a technique was proposed and evaluated for detection of metallic posts of parallel sides through a test body
of Z100 dental resin. The technique presented involves the acquisition and the image processing by trans-illumination of
the resin to detect the edges of the posts. LASER and LED systems in different colors were used as a source of
irradiation for the image formation. The qualitative analysis of the results showed that just by using LED in the red and
green colors it was possible to detect the edges of the posts. The results also showed that the use of LASER in this
experiment was not successful mainly due to the LASER light optical interference phenomenon inside the resin, which
resulted in low definition images. Lastly the discussion of the work was directed to the optical effects of absorption and
scattering of light throughout the resin, light diffraction through the posts and interference of the coherent light
evaluating the influence of each effect in the experiment.

We applied two new spectroscopic techniques (time-gated Raman microscopy and excitation-emission fluorescence
microspectroscopy) to characterize healthy and carious dental tissues. These methods were used together with visual
inspection, DIAGNOdent, optical polarization microscopy, scanning electron microscopy, and chemical microanalysis to
get a more detailed picture of chemical and structural transformations in dental tissues as a result of caries development.

A new multi-wavelength optical-plethysmograph has been designed to study the relation between the transmitted
optical density (OD) of the tooth vs. hemoglobin (Hb) content and oxygen saturation (SO2) of the pulpal blood using the
467, 506, 522 and 810 nm light emitting diodes (LEDs). The experimental model utilized the extracted human upper
incisor where the pulp cavity was filled with the blood having various values of Hb and SO2. A resin cap was made to
fit the tooth crown and optical fibers for transmission measurement. The LEDs were pulsed sequentially at 520 Hz with
the pulse duration of 240 μs. The OD as a function of Hb for the isosbestic wavelengths of 506 and 522 nm increased
almost linearly from 8.0 to 11.0 for Hb changing from 0.0 (saline control) to 2.5 g/dL, but beyond 2.5 g/dL no change
was observed. At 810 nm, the OD increased linearly till Hb of 13.4 g/dL, but its change was much smaller with 1.0 OD
per 13.4 g/dL. As for SO2, the OD at 467 nm with Hb of 1.0 g/dL that simulated the mean pulpal Hb content in vivo
varied by about 1.0 for SO2 changing from 100 to 40%. The OD change with respect to Hb change at 506 and 522 nm
showed better sensitivity than that at 810 nm. The combination of 467 and 506 or 522 nm wavelengths can provide a
noninvasive measurement of both pulpal Hb content and SO2 to diagnose pulp vitality of teeth in vivo.

Fiber-reinforced composites are new materials which have been used for a variety of dental applications, including tooth
splinting, replacement of missing teeth, treatment of dental emergencies, reinforcement of resin provisional fixed
prosthodontic restorations, orthodontic retention, and other clinical applications. Different fiber types are available, but
little clinical information has been disseminated. The traditional microscopy investigation, most commonly used to study
this material, is a destructive technique, which requires specimen sectioning and are essentially surface measurements.
On the basis of these considerations, the aim of this research is to analyze the interior of a dental sample reinforced with
fiber after a mechanical and thermal cycling to emulate oral conditions using optical coherence tomography (OCT). The
device we are using is a home built Fourier domain OCT working at 800 nm with 6 &mgr;m resolution. The results are
compared with microscopy images to validate OCT as a working method. In long term, fractures allow bacterial invasion
provoking plaque and calculus formation that can cause caries and periodontal disease. Therefore, non invasive imaging
of the bridge fiber enables the possibility of periodic clinical evaluation to ensure the patient health. Furthermore, OCT
images can provide a powerful method for quantitative analysis of crack propagation, and can potentially be used for in
vivo assessment.

This work presents a study to understand the interaction between Er:YAG laser and composite resin. The main purpose is the development of a new ultra-conservative clinical technique: differential ablation for composite resin restorations using Er:YAG laser. A hybrid composite resin (Z100, 3M, USA) formatted as tablets recently cured was used and after artificial aging method the teeth were irradiated with a Er:YAG laser and two different conditions were considered, energy level per pulse (100, 300 and 500mJ), frequencies (5, 10 and 15Hz) and different water fluxes. Diameter and depth of each resulted microcavity was measured and the material removed volumes were calculated. The resulted values were plotted and feted to allow a comparative observation of the material removed as a function of energy level per pulse. Frequencies of 5 and 10Hz were similar between them and seemed to allow the highest material ablated volume, however considering the energy per pulse parameter, 300mJ was more efficient than the others, mainly when water flux was around 0.1ml/s. The highest water flux showed lower ablation rate with the lowest fluency. Water fluxes presented an important factor considering composite ablation, even because it could modulate depth and surface regularity of the irradiated material.

The violet diode laser (405nm) has recently begun to be studied for surgical use and authors reported the soft tissue
could be effectively incised by irradiation power of even less than 1W. The wavelength of this laser is highly absorbed
by hemoglobin, myoglobin or melanin pigment. Cutting or ablating soft tissues by lower irradiation power might be
preferable for wound healing. The CO2 laser is known to be preferable for low invasive treatment of soft tissues and
widely used. The CO2 laser light (10.6μm) is highly absorbed by water and proper for effective ablation of soft tissues.
In this paper, we report the comparison of the violet diode laser with the CO2 laser in surgical performance of soft
tissues. Tuna tissue was used as an experimental sample. In the case of the violet diode laser, extensive vaporization of
tissue was observed after the expansion of coagulation. Carbonization of tissue was observed after the explosion. On the
other hand, consecutive vaporization and carbonization were observed immediately after irradiation in the case of CO2
laser. The violet diode laser could ablate tissue equivalently with the CO2 laser and coagulate larger area than the CO2
laser. Therefore the violet diode laser might be expectable as a surgical tool which has excellent hemostatis.

Free running and Q-switch infrared Er:YAG laser radiations were compared in the case of hard tissue preparation. The
interaction energy of 40 mJ in pulse 200 us long yielding to the interaction intensity 62 kW/cm2, and the energy of 20 mJ
in 100 ns long pulse yielding to the interaction intensity 62 MW/cm2 was used for the case of free running, and Q-switch
regime, respectively. For the radiation delivery, waveguide transfer system was used. It consisted of input lens (40 mm
focal length), a cyclic olefin polymer coated silver hollow glass waveguide (700/850 um diameter), and output lens (55
um focal length). For the interaction experiment the samples of the extracted human teeth cut into longitudinal sections
and polished were used. The thickness of the prepared samples ranged from 5 to 7 mm. The methods were compared
from the point of prepared cavity shape (SEM), inner surface, and possibility of selective removal of carries. The
composite filling material was used to reconstruct the cavities.

Laser treatment is a promising technique for dental applications such as caries removal, dental hypersensitivity
reduction and improvement of the bond strength between dentin and restoration materials. In this study the
topographic and morphological changes induced in enamel and dentin surfaces by treating with KrF excimer
laser radiation were studied as a function of the number of laser pulses and radiation fluence by scanning electron
microscopy and optical profilometry. For enamel, independently of the fluence used, material removal occurs
preferentially at the prisms sheaths, leading to the formation of surface pits of a few micrometers. For dentin,
a cone-like topography develops when the tubules are approximately parallel to the laser beam direction and
the radiation fluence is within the range 0.5 to 1.5 J/cm2. For higher fluences, the treated surfaces are flat and
covered with a layer of re-solidified materials.

We have shown that the enamel of the tooth is almost completely transparent near 1310-nm in the near-infrared and
that near-IR (NIR) imaging has considerable potential for the optical discrimination of sound and demineralized
tissue and for observing defects in the interior of the tooth. Lasers are now routinely used for many applications in
dentistry including the ablation of dental caries. The objective of this study was to test the hypothesis that real-time
NIR imaging can be used to monitor laser-ablation under varying conditions to assess peripheral thermal and
transient-stress induced damage and to measure the rate and efficiency of ablation. Moreover, NIR imaging may
have considerable potential for monitoring the removal of demineralized areas of the tooth during cavity
preparations. Sound human tooth sections of approximately 3-mm thickness were irradiated by a CO2 laser under
varying conditions with and without a water spray. The incision area in the interior of each sample was imaged
using a tungsten-halogen lamp with band-pass filter centered at 131--nm combined with an InGaAs focal plane
array with a NIR zoom microscope in transillumination. Due to the high transparency of enamel at 1310-nm, laser-incisions
were clearly visible to the dentin-enamel junction and crack formation, dehydration and irreversible
thermal changes were observed during ablation. This study showed that there is great potential for near-IR imaging
to monitor laser-ablation events in real-time to: assess safe laser operating parameters by imaging thermal and
stress-induced damage, elaborate the mechanisms involved in ablation such as dehydration, and monitor the
removal of demineralized enamel.

It has been previously demonstrated that short &lgr;=355-nm laser pulses can be used for the selective removal of caries
lesions and composite restorative materials from occlusal surfaces with minimal damage to the peripheral sound
tooth structure. One advantage of laser-systems is they can be integrated with acoustic and optical feedback systems
for the automated discrimination of dental caries and restorative materials. The objective of this study was to test
the hypothesis that root caries could be selectively removed from tooth surfaces using a computer controlled laserscanning
system coupled with an acoustic feedback system. Dental root caries surfaces on extracted teeth were
scanned with &lgr;=355-nm laser pulses at irradiation intensities ranging from 0.6 to 0.8 J/cm2. Acoustic feedback
signals were acquired and used to control the laser output and scanning stages were used to position the laser over
carious dentin until all the caries were removed to a fixed depth. Polarization optical coherence tomography (PSOCT)
was used to acquire images of the root caries lesions before and after removal by the laser in order to assess if
ablation was selective. The amplitude of the acoustic waves generated during the ablation of carious dentin was
higher than for sound dentin allowing the acoustic feedback system to discriminate between sound and carious
dentin. PS-OCT showed that caries were removed to a depth of up to 1.5-mm with minimal peripheral damage to
peripheral sound dentin. The acoustic feedback was successfully used to distinguish between root caries and sound
dentin, enabling the selective removal of caries from dentin surfaces using a &lgr;=355-nm, Nd:YAG Q-switched laser
system.

Samples of bone, dentin and enamel were stored in distilled water, 10% neutral buffered formalin, 70% ethyl alcohol or
6% sodium hypochlorite solutions for fifteen days. Other samples were stored in the same solutions for 36 hours and
then transferred to distilled water for the remainder of the fifteen day period. Finally, samples than had been stored dry
for up to 5 years were rehydrated and ablated. All enamel specimens appeared unaffected by the storage conditions.
Dentin samples were very significantly affected by all storage methods. Bone samples were affected by most storage
conditions. Samples stored in sodium hypochlorite had as much as a 100 percent increase in ablation rate. Surprisingly,
dry stored samples that were reconstituted for 36 hours ablated at virtually the same rate as those stored in distilled
water. None of the storage conditions studied produced ablation rates that mirrored in vivo ablation. Sterilization by
autoclave is the only reliable and safe method studied but cannot be used on teeth with amalgam fillings for safety
reasons. Teeth with fillings should be stored in 10% neutral bufferred formalin for a minimum of one week.

Ultrashort-pulsed laser (USPL) can ablate various materials with precious less thermal effect. In laser dentistry, to solve
the problem that were the generation of crack and carbonized layer by irradiating with conventional laser such as
Er:YAG and CO2 laser, USPL has been studied to ablate dental hard tissues by several researchers. We investigated the
effectiveness of ablation on dental hard tissues by USPL. In this study, Ti:sapphire laser as USPL was used. The laser
parameter had the pulse duration of 130 fsec, 800nm wavelength, 1KHz of repetition rate and the average power density
of 90~360W/cm2. Bovine root dentin plates and crown enamel plates were irradiated with USPL at 1mm/sec using
moving stage. The irradiated samples were analyzed by SEM, EDX, FTIR and roughness meter. In all irradiated
samples, the cavity margin and wall were sharp and steep, extremely. In irradiated dentin samples, the surface showed
the opened dentin tubules and no smear layer. The Ca/P ratio by EDX measurement and the optical spectrum by FTIR
measurement had no change on comparison irradiated samples and non-irradiated samples. These results confirmed that
USPL could ablate dental hard tissue, precisely and non-thermally. In addition, the ablation depths of samples were
10&mgr;m, 20&mgr;m, and 60&mgr;m at 90 W/cm2, 180 W/cm2, and 360 W/cm2, approximately. Therefore, ablation depth by USPL
depends on the average power density. USPL has the possibility that can control the precision and non-thermal ablation
with depth direction by adjusting the irradiated average power density.

In this study, we investigated the role of water spray. To ablate human enamel tissue, a
long-pulsed Er,Cr:YSGG laser was used at various radiant exposures. During dental ablation,
distilled water was sprayed to the sample surface. Desiccated samples were also tested with
direct irradiation for comparison. In order to identify dominant ablation mechanisms, transient
acoustic waves were measured using a piezoelectric microphone. Enamel ablation efficiency
was evaluated with Optical Coherence Tomography (OCT). Material removal was up to four
times larger at the best flow rate with respect to ablation without spray. In spite of 60 % higher
damage threshold by water absorption, spray ablation enhanced both the laser-induced acoustic
transients up to six times and the ablation efficiency up to twice over the entire range of radiant
exposures tested, compared to dry ablation. The improved pressure and ablation performance of
the spray-assisted process with cooling effect were thought to be induced by recoil stress, rapid
water vaporization, interstitial water explosion, and/or liquid-jet formation. Spray ablation along
with water cooling and abrasive mechanical effects can be a safe and efficient modality for
dental treatment.

The present study aimed to compare root caries removal by air turbine and Er,Cr:YSGG laser, and examine
morphological changes after these caries removal techniques under scanning electron microscopy (SEM). Seventy two
extracted human carious-free third molars were used in this study. After the in vitro root caries induction using S.
mutans, the carious lesions were removed by the conventional technique, using burs (control), and by the Er,Cr:YSGG
laser, using 13 different parameters, between 1 and 4,0 W. During caries removal, preparation time was recorded for all
groups. The results appointed out that the conventional method was the fastest one. When only laser treatment was
evaluated, the higher parameters seemed to remove caries faster then the lower ones. SEM revealed that the surfaces
treated by air turbine were smooth, but with debris. The laser groups demonstrated smooth undulations, with little or
absence of smear layer, and no signs of carbonization. These results suggest that caries removal by Er,Cr:YSGG laser
was effective. Therefore, this equipment requires training on cavity preparation, in order to avoid damages in dental hard
tissues.

Laser systems of various wavelengths and pulse characteristics have been introduced in dentistry. At present, the range
of applications for the different systems is being investigated mainly differentiating between soft and hard tissue
applications. For the preparation of root canals both hard and soft tissues are involved. Ideally, one would like to use
one laser system for the whole treatment.
In this study, we studied the characteristics of the pulsed 2,78 Er,Cr:YSGG laser (Biolase, Waterlase Millenium), in
view of root canal cleaning and desinfection. The laser energy was fiber delivered with fiber tip diameters from 400 &mgr;m
down to 200 &mgr;m.
Special thermal and high speed imaging techniques were applied in a transparent model of a tapered root canal and
slices cut from human teeth.
High speed imaging revealed the dynamics of an explosive vapor bubble at the tip of the Er laser in water and the root
canal model. Typically for Erbium lasers, within a time span of several hundred &mgr;s, a longitudinal bubble expanded to
maximum size of 5 mm length and 2 mm diameter at 100 mJ and imploded afterwards. In the root canal, the explosive
bubble created turbulent high speed water streaming which resects soft tissue from the hard tissue. Thermal imaging
showed the dynamics of all lasers heating of the canal wall up to several mm depending on the wavelength and energy
settings.
The mechanism of smear layer removal and sterilization in the root canal, is attributed to cavitation effects induced by
the pulsed laser. The heat generation into the dentine wall was minimal.

Studies in cariology have been struggling for the development of caries prevention techniques, precocious diagnoses of
lesions, re-mineralization of incipient carious lesions and early restorative intervention with minimally invasive
procedures. When removing caries, healthy dental structure is often removed inadvertently during its final phase, for
being quite difficult to precise the limits between viable and decayed dental tissues clinically. With laser technologies, a
subjective clinical hint, often used to indicate when tissue ablation should be stopped is that different sounds are
perceptive whether in carious (bass) or in healthy (treble) dental structure; when sound produced by ablation turned
treble it would mean that healthy tissue was reached. This study aims to classify those audio differences and to turn
them into objective parameters for a conservative operative dentistry with minimally invasive tissue removal when
using erbium lasers. Twenty freshly extracted human teeth were used (10 decayed and 10 sound teeth). Dentine was
erbium laser irradiated under same parameters, distance and refrigeration and a mono directional microphone was set 10
cm far from the operative area in order to capture and record the ablation produced sounds when working either on
carious or healthy dentine. Ten pulses per file were then analysed in a computer software (200 analyses). It was
permitted to draw similarities among the patterns in each group (decayed and healthy teeth) as well as differences
between decayed and healthy produced sounds. Audio analysis came out to be a technical reliable objective parameter to
determine whether laser ablated dentine substrates are decayed or sound; therefore it can be proposed as a conservative
parameter, avoiding unnecessary removal of healthy dentine and restricting it to carious one.

This study evaluated the molecular and morphological changes on dentin elements after the Er:YAG laser irradiation. Six
human third molars were selected and the occlusal one-third of the crown was removed. The dentin surface was
schematically divided into areas corresponding to four surface treatments groups: Control (Group C): 37% phosphoric
acid etching; Group I: Er:YAG laser 80mJ; Group II: Er:YAG laser 120mJ; Group III: Er:YAG laser 180mJ. The
characterization was performed by Scanning Electron Microscopy (SEM) and Fourier-Transformed Raman Spectroscopy
(FT-Raman) before and after the treatments. A reduction of the relative intensity for the spectra was observed in the
Group II and III samples. The SEM photomicrographies revealed open dentin tubules in the control group specimens.
The groups I, II and III presented partially open dentin tubules. SEM images showed that the laser-irradiated dentin
surface was not favorable to the diffusion of monomers. The chemical information obtained by Raman spectroscopy
showed that higher laser energies (180 mJ) affected more the phosphate, carbonate and the organic components of
dentin.

Polarization sensitive optical coherence tomography (PS-OCT) and near-IR (NIR) imaging are promising new
technologies under development for monitoring early carious lesions. Fluorosis is a growing problem in the U.S.,
and the more prevalent mild fluorosis can be visually mistaken for early enamel demineralization. Some initial NIR
images suggest that enamel defects and dental caries manifest different optical behavior in the NIR. Unfortunately,
there is little quantitative information available regarding the differences in optical properties of sound enamel,
enamel developmental defects, and demineralized enamel due to caries. This study tested the hypothesis that
hypomineralized enamel due to fluorosis can be differentiated from demineralized enamel due to caries using NIR
and PS-OCT imaging because of different optical behavior in the NIR. Thirty extracted human teeth with various
degrees of suspected fluorosis and/or caries were imaged using PS-OCT and NIR transillumination. An InGaAs
camera and a near-IR diode laser were used to measure the optical attenuation through transverse tooth sections
(~200 &mgr;m). Developmental defects were clearly visible in the polarization-resolved OCT images, demonstrating
that PS-OCT can be used to nondestructively measure the depth and possible severity of the defects. Enamel defects
on whole teeth that could be imaged with high contrast with visible light were transparent in the near-IR while
demineralized areas due to caries were opaque. In contrast, dental caries could be clearly distinguished from sound
enamel. This study suggests that PS-OCT and NIR methods may potentially be used as tools to assess the severity
and extent of enamel defects and for the differentiation of mild fluorosis defects from early carious lesions.

Laser removal of dental hard tissue can be combined with optical, spectral or acoustic feedback systems to
selectively ablate dental caries and restorative materials. Near-infrared (NIR) imaging has considerable potential for
the optical discrimination of sound and demineralized tissue. The objective of this study was to test the hypothesis
that two-dimensional NIR images of demineralized tooth surfaces can be used to guide CO2 laser ablation for the
selective removal of artificial caries lesions. Highly patterned artificial lesions were produced by submerging 5 x 5
mm2 bovine enamel samples in demineralized solution for a 9-day period while sound areas were protected with
acid resistant varnish. NIR imaging and polarization sensitive optical coherence tomography (PS-OCT) were used
to acquire depth-resolved images at a wavelength of 1310-nm. An imaging processing module was developed to
analyze the NIR images and to generate optical maps. The optical maps were used to control a CO2 laser for the
selective removal of the lesions at a uniform depth. This experiment showed that the patterned artificial lesions
were removed selectively using the optical maps with minimal damage to sound enamel areas. Post-ablation NIR
and PS-OCT imaging confirmed that demineralized areas were removed while sound enamel was conserved. This
study successfully demonstrated that near-IR imaging can be integrated with a CO2 laser ablation system for the
selective removal of dental caries.

Previous studies have demonstrated that Polarization Sensitive Optical Coherence Tomography (PS-OCT) can be used
to image early dental caries. The purpose of this study was to compare the measured integrated reflectivity of natural
caries lesions with the mineral loss measured using digital microradiography in order to determine if PS-OCT can be
used as a nondestructive in vivo method to measure the severity of dental decay in the important occlusal surfaces. A
PS-OCT system operating at 1310-nm was used to acquire polarization resolved images of natural caries lesions on the
occlusal surfaces of extracted teeth. The integrated reflectivity from lesion areas was compared to the integrated
mineral loss from the same lesion area measured using digital microradiography. There was a strong correlation
between the integrated mineral loss of the caries lesion measured using high resolution digital microradiography and the
integrated reflectivity in the perpendicular polarization axis of the PS-OCT system demonstrating the potential for this
method to nondestructively monitor the severity of caries lesion in the occlusal pit and fissure where most new decay is
found. Although we find these results encouraging, we desire a higher correlation between the integrated mineral loss
and the integrated reflectivity and we believe a higher correlation is attainable with better matching of the PS-OCT
scans and the histological thin sections.

Pemphigus vulgaris is a chronic, autoimmune, blistering disease of the skin and mucous membranes with a potentially
fatal outcome. In this case micro-Raman spectroscopy (&mgr;-RS) can provide a powerful tool for a not invasive analysis of
biological tissue for biopsy and in vivo investigation. Based on the evaluation of molecular vibration frequencies, the
&mgr;-RS is able to detect the main molecular bonds of protein constituents, as the C-H and C-C ones. Changes in frequency
or in the relative intensity of the vibration modes revealed by &mgr;-RS can be related to changes of chemical bond and of
protein structure induced by pathology. Quantitative information on the intensity variation of specific Raman lines can be
extracted by Partial Least Square (PLS) analysis. &mgr;-RS was performed on some samples of oral tissue and blood serum
from informed patients affected by pemphigus vulgaris (an oral pathology) at different pathology stages.
The spectra were measured by means of a Raman confocal microspectrometer apparatus using the 633 nm line of a He-
Ne laser source. The main protein bonds are clearly detectable in the considered samples giving important information
on the integrity and on the state of tissue and blood serum components (lipids and proteins), and consequently on the
occurrence of pathology.

This study evaluated ex vivo the influence of the number of gel/LED-laser applications/activations on cervical
microleakage of two different barrier materials used for protection during whitening of endodontically treated teeth.
Eighty-four canines were instrumented and obturated with epoxy resin sealer. The seal was removed 2 mm beyond the
cemento-enamel junction for barrier placement and the teeth were divided into two groups of 40 teeth each: G1, zinc
phosphate cement; G2, glass ionomer cement. The two groups were subdivided into 4 subgroups (n=10 each): I) no gel or
LED-laser application; II) one gel application and two LED-laser activations; III) two gel applications and four LED-laser
activations; IV) three gel applications and six LED-laser activations. The teeth were immersed in India ink for 7
days, decalcified and cleared. Cervical microleakage was quantified with a measurement microscope. Statistical analysis
showed that zinc phosphate caused significantly lower microleakage than glass ionomer cement (presented microleakage
in all subgroups). However, after two (p<0.01) and three (p<0.001) applications of gel, there was statistially significant
microleakage in zinc phosphate barriers. Based on the present results, it can be concluded that cervical barriers with zinc
phosphate cement show less cervical microleakage and that two or more applications/activations of gel/LED-laser
significantly increase microleakage.

The dental bleaching is known for many years. Recently a technique employing light has
open up new and exciting possibilities. Besides its vast application there are still many
important points to be understood about teeth photon bleaching. In this work we present an
"in vitro" experiment to explore the main mechanisms involved during the photon action in
tooth whitening. Our results indicated that light at same wavelengths are great absorbed by
pigments creating a local heating which considerably increase the bleaching rate. This
results in a fast reaction without heating the whole dental structure. We discuss details of
our experiment. Work supported by Fapesp and CNPq.

Selection of the proper shade and color matching of restorations to natural dentition continues to be one of the most frustrating problems in dentistry and currently available shade guide presents a limited selection of colors compared to those found in natural dentition.
This investigation evaluation if the composites resins shade B2 are equivalent to the Vita shade guide B2.
Twelve composite resins (Renamel Microfill Super Brite- Cosmedent USA, Renamel Universal Brite- Cosmedent USA, Renamel Microfill Body- Cosmedent USA, Renamel Universal Body- Cosmedent USA, Opallis EB2-FGM, Opallis DB2-FGM, Filtek Supreme XT-3M/ESPE, Filtek Z250-3M/ESPE, Filtek Z350-3M/ESPE, Z100-3M/ESPE, 4 Seasons Dentin-Ivoclar/Vivadent, Tetric Ceram-Ivoclar/Vivadent) shade B2 were used. From each composite, two specimens were made in a steel matrix with 8.0 mm diameter and 10.0 mm different predetermined thickness (0.2, 0.4, 0.6, 0.8, 1.0, 1.2, 1.4, 1.6, 1.8, 2.0 mm). The specimens were 40 seconds light polymerized by LED Ultrablue (DMC). The specimens were measured 10 times each to determine the shade using a reflectance spectrophotometer (Pocket Spec).
According to results was verified that not any of composites resins shade B2 evaluated in this study presented values of color difference (ΔE) equivalent to the Vita shade guide B2 and the 2 mm thickness showed the closer match to the Vita shade guide B2.

A major characteristic of LEDs systems is the lower heat emission related with the kind of light
generation and spectral emission band. Material temperature during photoactivation can promote
different photocuring performance. Organic dye penetration could be a trace to identify the efficacy of
photocured composite resin. A new method using fluorescent spectroscopy through digital image
evaluation was developed in this study. In order to understand if there is a real influence of material
temperature during the photoactivation procedure of a dental restorative material, a hybrid composite
resin (Z250, 3M-Espe, USA) and 3 light sources, halogen lamp (510 mW/cm2) and two LED systems 470±10nm (345 and 1000 mW/cm2) under different temperatures and intensities were used. One thousand and five hundred samples under different associations between light sources and temperatures (0, 25, 50, 75 and 100oC were tested and immediately kept in 6G rodamin dye solution. Dye penetration was evaluated through fluorescent spectroscopy recorded by digital image data. Pixels in gray scale showed the percentage penetration of organic dye into the composite resin mass. Time and temperature were statistically significant (p<0.05) through the ANOVA statistical test. The lowest penetration value was with 60 seconds and 25oC. Time and temperature are important factors to promote a homogeneous structure polymerized composite resin more than the light source type, halogen or LEDs system.

In this work the color dependence of resin composites with the background color was evaluated. The objective was to
measure since what thickness the color of the sample stops being influenced by the color of the background over which
the resin is placed and the methodology used in experiment was based in analyzing the contrast of digital images of the
sample over a black background. The results shown that since 0.8 mm the images contrast becomes almost constant; it
prove that since this thickness the color of resin composite depends on the optical resin properties only. The experiment
was repeated under three conditions of luminosity to evaluate the influence of it on the image contrast and the results
obtained were identical.